Current MWD pulser technology includes pulsers that are sensitive to different fluid pump down hole pressures, and flow rates, and requires field adjustments to pulse properly. These pulsers deliver fairly low amplitude pressure pulses for the amount of energy they use to engage. “Stick-slip” is a well known phenomenon that refers to a situation that occurs when the lower part of the drill string & the drill bit, which is normally rotating with the drill string, gets stuck “stick” in the formation and the drill string continues to rotate rapidly building up torque that eventually causes the drill bit to rotate excessively “slip” and to stop again to the point that it wears out the bit prematurely and decreases the rate of drilling. The pulse magnitude and axial jerk of our PFD device will reduce or eliminate “stick slip.”
Coiled tubing drill strings with downhole motors powered by drilling fluids are restricted by the amount of pressure that can be tolerated inside the coiled tubing. The axial jerk on the bit and hydraulic amplification of this flow throttling device (FTD) allows for increased jetting and removal of cuttings at the bit, where the pressure pulses and weight on the bit are most needed.
Increased rate of penetration of the drill bit leads to lower drilling costs. The increased jetting action clears away the cuttings during drilling which may cause the drill string to become stuck in the hole if not removed from the annular drill collar flow channel between the drill pipe and the formation. Removing these cuttings will reduce the NPT (non-productive time) associated with the drill string getting stuck in the hole when cuttings build up. The flow throttling device (FTD) may optionally be set so that the pressure pulses downhole are hydraulically amplified so that the formation is fractured to increase the permeability of the formation of interest and extend the flow channels further outward away from the drill bore, thus increasing the surface area of the formation from which hydrocarbons can be produced. This fracturing while drilling or after drilling (with a formation isolation mechanism similar to a pack which will be referred to as a packer isolation mechanism (PIM)) can be used selectively, depending on whether the operator wants to produce the well while drilling, or fracture the formation of interest through liners or perforations subsequent to the drilling operation. Use of a single uphole pump (frac truck) may be possible in this case and this represents a dramatic capital and labor savings uphole compared with conventional technology. Since the pulses can be adjusted to be large enough to be read uphole through an annular pressure transducer, the use of a gamma ray detector directly above the bit in conjunction with the pulser can be used to maintain the drill string within the formation of interest. The gamma ray detector is located several feet above the drill bit so that when the bit strays outside the formation of interest, the driller can more quickly correct direction and thereby maximize the time within the pay zone.
Because the bottom hole assembly is typically in compression, the FTD, will also, for a short period of time, release some of that compression on the drill string when it generates its large pressure pulse downhole, similar to a snake coiling and uncoiling. This coiling and uncoiling effect known as “axial jerk” also produces the added benefit of drilling a straighter hole. Additionally, the FTD will have a tendency to “pick” forward straight through formation induced deviations. The benefits of drilling a straighter hole include allowing for the FTD to spend less time stuck in the hole; more accurate placement of the bit into the formation of interest thus enhancing recovery efficiencies; less time correcting direction when the drill string wanders off course; less mechanical inefficiencies caused by the drill string rubbing against the side of the 20 hole if the hole is not vertical; less wear on the drill string during drilling; and an overall increase in the ROP (rate of penetration) primarily due to drilling a straighter hole.
Among the many advantages of the present disclosure are that it includes embodiments of devices with decreased sensitivity to fluid flow rate or pressure within limits, does not require field adjustment, and is capable of creating recognizable, repeatable, reproducible, clean (i.e. noise free) fluid pulses using minimum power due to a unique flow throttling devices (FTD) that may partially be powered by magneto-electric and turbine generated energy systems as well as a unique pilot flow channel design. The annular drill collar flow channel is specifically designed such that Tprimarily laminar flow exists in the area where the pulse occurs. Additional pulsers with varying pressure amplitudes and/or frequencies are easily added to enable an exponential increase in the bit amplitude and/or pulse rate.
Additionally, in comparison with earlier devices designed for addressing the same or similar needs, the devices of the present disclosure provide larger pressure pulses due to the fact that the design allows for closing of 100% of the fluid flow stream with a pulser bell portion of the flow throttling device (FTD). Other earlier developed devices possess different failure mechanisms that include closing valves and utilizing operating springs with by-pass channels, which are unnecessary for the devices of the present disclosure. In fact, the failure mechanism for the devices of the present disclosure includes a flow throttling device (FTD) that exists in the open state when not functioning. The need for a by-pass channel design is optional for the present devices.
The present disclosure includes devices which provide a higher bit rate and potentially more easily controlled pulses which can utilize downhole pressure transducers that are energized with an electrical circuitry control package. Instead of valves, the flow throttling devices (FTD's) utilized allow for a more controlled opening of channels for the fluid flow and therefore the frequency, duration, and amplitude of the pulses can be provided as needed by a knowledgeable operator. The amplitude may be adjusted by keeping the pulser bell from closing off fluid channel flow completely. In fact, the bell itself may provide channel opening and closing vents or ducts.
The pulse generated by the present devices also is not required to be periodic, but could be “aperiodic” in that the residence frequency is also controllable. In addition, it is possible to design these devices such that they are in combination with a gamma ray or other sensor system detectors which also utilize the electrical circuitry control package.
It is a general object of the present disclosure to provide improved flow pulsing methods and apparatus for various applications wherein vibrating and/or flow pulsing effects are desired, for example, vibrating a drill string and a drill bit to increase the drilling rate and to pulse the flow of drilling fluid emitting from the drill bit jets thereby to enhance the cleaning effect and the drilling rate.
An additional objective is to provide apparatus that would allow the continuation of the drilling process without the benefit of the pulsating flow, in the event that the restricting member fails in operation and remains in the opened position.
Accordingly, the present disclosure in one aspect provides a flow pulsing apparatus including a housing providing a passage for a main flow of fluid and a means for periodically interrupting the flow through main passage to create pulsations in the flow with a time delay between pulses and a cyclical water-hammer effect to vibrate the drill string during use.